基于细观尺度的岩体开挖渐进破坏模拟研究

Progressive Failure Process of Rock Excavation Based on Meso-Mechanical Method

岩土渐进式地质灾害是当前岩土工程领域的重要研究课题。基于颗粒离散元法导出颗粒连接损伤模型,建立岩石细观离散模型,进行不同颗粒参数条件下的岩石单轴受压数值模拟。结果表明,岩石细观颗粒间相互黏结力是影响颗粒黏结破坏的主要因素;颗粒间摩擦系数是影响宏观强度的敏感参数,单轴受压试验形成接近45°剪切带,数值模拟与试验结果较好吻合,验证了该模型的合理性。建立岩体开挖细观离散模型,模拟不同地层条件下的开挖过程,对比分析了开挖未支护和支护情况下检测点的沉降差异。研究发现,未支护支撑下,深层开挖时,检测点的位移沉降较浅层开挖时明显;支护可以有效降低围岩变形,防止拉应力产生。本文从细观上揭示岩体开挖条件下渐进式破坏过程形成机制,为更深入研究岩土力学特性和滑动断裂的形成与发展等渐进破坏过程提供了理论和技术支撑。

The progressive failure of geotechnical engineering field is an important research subject. Based on the particle discrete element method, the particle connected damage model is deduced. This paper establishes the rock mesoscopic discrete model and studies the uniaxial corn pression numerical simulation under different particle parameter conditions. The results show that the bonding force is the main factor of bond failure. Friction coefficient among particles is a sensitive parameter influencing the macroscopic strength. Uniaxial compression test forms a shear zone close to 45°. The results of numerical simulation match the experimental results well, and this proves the model is reasonable. This paper establishes the excavation mesoscopic discrete model, simulates different formation conditions of the excavation process and analyses the settle- ment difference between the excavations with supporting and without supporting. The study finds that the unsupported deep excavation under a shallow excavation testing point has obvious settlement. Supported rock can effectively reduce the surrounding rock deformation and prevent stress increasing. This paper reveals the rock progressive failure mechanism under excavation and provides a theoretical and technical support for further study of geotechnical engineering mechanic characteristics, rock fracture and progressive failure process.